Semiconductor light source

ABSTRACT

A semiconductor light source is disclosed. In one embodiment, a semiconductor light source includes at least one semiconductor laser configured to generate a primary radiation and at least one conversion element configured to generate a longer-wave visible secondary radiation from the primary radiation, wherein the conversion element includes a semiconductor layer sequence having one or more quantum well layers, wherein, in operation, the primary radiation is irradiated into the semiconductor layer sequence parallel to a growth direction thereof, with a tolerance of at most 15°, wherein, in operation, the semiconductor layer sequence is homogeneously illuminated with the primary radiation, and wherein a growth substrate of the semiconductor layer sequence is located between the semiconductor layer sequence and the semiconductor laser, the growth substrate being oriented perpendicular to the growth direction.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a divisional application of U.S. application Ser. No.16/075,853, entitled “Semiconductor Light Source,” which was filed onAug. 6, 2018, which is a national phase filing under section 371 ofPCT/EP2017/055823, filed Mar. 13, 2017, which claims the priority ofGerman patent application 10 2016 104 616.7, filed Mar. 14, 2016, all ofwhich are incorporated herein by reference in its entirety.

TECHNICAL FIELD

A semiconductor light source is specified.

SUMMARY OF THE INVENTION

Embodiments provide a semiconductor light source which emits radiationthat can be directed efficiently into a specific spatial region and canbe adjusted in different colors.

According to at least one embodiment, the semiconductor light sourcecomprises one or more semiconductor lasers for generating a primaryradiation. In this case, it is possible to use a plurality ofstructurally identical semiconductor lasers or also a plurality ofdifferent semiconductor lasers, in particular, having different emissionspectra. The semiconductor light source preferably comprises exactly onesemiconductor laser.

According to at least one embodiment, the primary radiation, which isgenerated by the at least one semiconductor laser during operation, isultraviolet radiation or visible light. For example, a wavelength ofmaximum intensity is at least 250 nm or 320 nm or 360 nm or 400 nm or440 nm and/or at most 570 nm or 535 nm or 525 nm or 490 nm or 420 nm. Inparticular, the wavelength of maximum intensity of the primary radiationis 375 nm or 405 nm or 450 nm, in each case with a tolerance of at most10 nm.

According to at least one embodiment, the semiconductor light sourcecomprises one or more conversion elements. The at least one conversionelement is designed to generate a longer-wave visible secondaryradiation from the primary radiation. In other words, the conversionelement converts the primary radiation completely or partially into thesecondary radiation. In the intended use, the secondary radiation isemitted from the semiconductor light source and is perceived by a user.

According to at least one embodiment, the conversion element has asemiconductor layer sequence for generating the secondary radiation. Thesemiconductor layer sequence comprises one or more quantum well layers.The primary radiation is absorbed in the at least one quantum well layerand converted into the secondary radiation via charge carrierrecombination. In other words, the quantum well layers are excited tophotoluminescence by the primary radiation and thus optically pumped.

According to at least one embodiment, the quantum well layers are of athree-dimensional shape. This can mean that the quantum well layers orat least one of the quantum well layers or all quantum well layers, inparticular when viewed in cross section, have one or more kinks. Thequantum well layers or at least some of the quantum well layers arethen, viewed in cross section, not configured as uninterrupted straightlines.

According to at least one embodiment, at least one, some or all of thequantum well layers, viewed in cross section, are arranged in places orcompletely obliquely to a growth direction of the semiconductor layersequence of the conversion element. In other words, the quantum welllayers are oriented neither parallel nor perpendicular to the growthdirection, at least in certain regions or even entirely.

According to at least one embodiment, at least one, some or all of thequantum well layers, viewed in cross section, are arranged in places orcompletely perpendicular to the growth direction of the semiconductorlayer sequence of the conversion element. The respective quantum welllayers can be restricted to the base regions and can be designed ascontinuous layers, or can be located only within the semiconductorcolumns, or else both.

In at least one embodiment, the semiconductor light source comprises atleast one semiconductor laser for generating a primary radiation and atleast one conversion element for generating a longer wavelength, visiblesecondary radiation from the primary radiation. In order to generate thesecondary radiation, the conversion element has a semiconductor layersequence having one or more quantum well layers. The quantum well layersare preferably shaped three-dimensionally, so that the quantum welllayers have kinks when viewed in cross section and/or are oriented atleast in places obliquely to a growth direction of the semiconductorlayer sequence.

In the semiconductor light source described here, an efficient,radiation-generating semiconductor laser can be used as a light sourcefor the primary radiation. By means of the conversion element, in thecase of a specific semiconductor laser for generating the primaryradiation, an emission wavelength range can be set by using quantum welllayers that can be configured differently. By using photoluminescentquantum well layers in the conversion element, a high conversionefficiency can be achieved and the desired spectral properties of thesecondary radiation can be specifically set by a design of the quantumwell layers. A highly efficient, colored semiconductor light source,which can also be scaled in size, can thus be achieved, in particularwith a directional emission characteristic.

In contrast, other scalable light sources having a directional emissioncharacteristic such as vertically emitting semiconductor lasers, that isto say with semiconductor lasers which emit in the direction parallel toa growth direction, have only a low efficiency. Light sources havingnanostructures and having a phosphor conversion layer likewise have acomparatively low conversion efficiency and cause difficulties inelectrical contacting and when coupling out light. White light-emittinglaser diodes which are provided with a phosphor require, as a rule, acomplex optical system in order to focus and efficiently couple lightout of the phosphor. Thus, such alternative solutions have a lowcomponent efficiency and a relatively low conversion efficiency, as wellas a more complex design, for instance with regard to electricalcontacting or optics.

According to at least one embodiment, a main emission direction of thesemiconductor light source is oriented parallel to the growth directionof the semiconductor layer sequence of the conversion element, with atolerance of at most 15° or 10° or 5°. An emission angle range of theconversion element has a half-width of at most 90° or 70°, so that lightis emitted more directional by the conversion element than in the caseof a Lambertian emitter. In the case of a Lambertian emitter, thefollowing applies to an intensity I as a function of an angle α andrelative to a maximum intensity I_(max): I(α)=I_(max) cos α. In the caseof a Lambertian emitter, the half-width of the emission characteristicis thus substantially greater.

According to at least one embodiment, the semiconductor laser and theconversion element are grown epitaxially independently of one another.That is to say that the semiconductor laser and the conversion elementare two components produced independently of one another, which are onlycombined in the semiconductor light source.

According to at least one embodiment, the conversion element and thesemiconductor laser do not touch each other. This can mean that anintermediate region with a different material is present between thesemiconductor laser and the conversion element. The intermediate regionis, for example, gas-filled or evacuated or bridged by a light guide ora transparent body such as a transparent semiconductor material.

According to at least one embodiment, in operation the primary radiationis irradiated into the semiconductor layer sequence perpendicular to thegrowth direction, with a tolerance of at most 15° or 10° or 5° or 1°. Inother words, the irradiation direction of the primary radiation can beoriented perpendicular to the main emission direction of the conversionelement. If, for example, the semiconductor laser has a Gaussian beamprofile when viewed in a cross section, the emission direction of thesemiconductor laser thus relates to the direction of maximum intensity.This can apply correspondingly to other emission profiles of the primaryradiation.

According to at least one embodiment, the primary radiation is emittedin a linear shape by the semiconductor laser or in an ellipticalemission characteristic or elliptical angular distribution or alsolinearly. This can mean that an aspect ratio of a width and a length ofthe primary radiation, in particular seen in the optical far field, isat least 2 or 5 or 10 or 50. A uniform illumination of the semiconductorlayer sequence of the conversion element can be achieved by such a lineprofile of the primary radiation.

According to at least one embodiment, the semiconductor laser isarranged such that a growth direction of the semiconductor laser isoriented perpendicular to the growth direction of the semiconductorlayer sequence. In this case, the growth direction of the semiconductorlaser is preferably parallel to a plane which is defined by thesemiconductor layer sequence. In other words, the growth direction ofthe semiconductor laser is oriented perpendicular to the growthdirection of the semiconductor layer sequence and thus parallel to aplane to which the growth direction of the semiconductor layer sequenceis perpendicular. This applies in particular to a tolerance of at most10° or 5° or 1°. Furthermore, the growth direction of the semiconductorlaser is preferably oriented perpendicular to the emission direction ofthe semiconductor laser, which in turn can be oriented perpendicular tothe growth direction of the semiconductor layer sequence of theconversion element.

According to at least one embodiment, the semiconductor laser is aso-called stripe laser, also referred to as a ridge laser. In this case,the semiconductor laser comprises at least one ridge which is producedfrom a semiconductor layer sequence of the semiconductor laser and whichserves as a waveguide for the primary radiation within the semiconductorlaser.

According to at least one embodiment, during operation, the primaryradiation is irradiated into the semiconductor layer sequence of theconversion element parallel to the growth direction of the semiconductorlayer sequence, with a tolerance of at most 10° or 5° or 1°. In thiscase, an emission direction of the semiconductor laser can be orientedparallel to the main emission direction of the conversion element. Ifboth primary radiation and secondary radiation are emitted from thesemiconductor light source, it is possible that a direction of theprimary radiation is not or not significantly changed after leaving thesemiconductor laser.

According to at least one embodiment, the conversion element has a baseregion. The base region is preferably a continuous, uninterrupted regionof the semiconductor layer sequence of the conversion element. Inparticular, the base region extends perpendicular to a growth directionof the semiconductor layer sequence. It is possible for the base regionto be free of quantum well layers. Alternatively, the quantum welllayers can be located in the base region.

According to at least one embodiment, the conversion element comprises aplurality of semiconductor columns. The semiconductor columns preferablyextend away from the base region, in the direction parallel to thegrowth direction of the semiconductor layer sequence.

According to at least one embodiment, the semiconductor layer sequence,in particular the base region, works as a waveguide for the primaryradiation within the conversion element. In particular, thesemiconductor layer sequence and/or the base region is/are designed as awaveguide in the direction perpendicular to the growth direction of thesemiconductor layer sequence.

According to at least one embodiment, the semiconductor columns, aswaveguides for the primary radiation, are aligned along the directionparallel to the growth direction and in particular also along thedirection parallel to the main emission direction of the conversionelement. Thus, by means of the semiconductor columns, an emissioncharacteristic and especially the main emission direction of theconversion element can be determined. The semiconductor columns arepreferably not a photonic crystal. The semiconductor columns differ froma photonic crystal in particular by means of larger geometric dimensionsand by an irregular or less regular arrangement.

According to at least one embodiment, the primary radiation passes fromthe semiconductor laser in a free-beam manner to the semiconductor layersequence. This can mean that there are no optics for the primaryradiation between the semiconductor layer sequence and the semiconductorlaser and/or a region between the semiconductor laser and thesemiconductor layer sequence is completely or predominantly evacuated orfilled with a gas. Predominantly can mean that an optical path betweenthe semiconductor laser and the semiconductor layer sequence is at least50% or 70% or 90% free of condensed matter.

According to at least one embodiment, the at least one quantum welllayer is applied to and/or on the semiconductor columns. In this case,the quantum well layers can imitate a shape of the semiconductorcolumns. In particular, the semiconductor columns form a core and thequantum well layers form a mantle. Such a structure is also referred toas a core-shell structure.

Any kinks in the quantum well layers, which may be present in crosssection, can result, for example, from the quantum well layers from sidesurfaces of the semiconductor columns bending in the direction towardsan upper side of the semiconductor columns and optionally also bendingback towards an opposite side surface. The quantum wells can follow acrystal structure of the underlying layers and/or of the rods.

According to at least one embodiment, the secondary radiation and/or theprimary radiation is/are radiated out of the semiconductor columns to atleast 50% or 70% or 85% at the tips of the semiconductor columns. Inother words, regions between the semiconductor columns and side faces ofthe semiconductor columns are dark or significantly darker, especiallyin comparison to the tips of the semiconductor columns.

According to at least one embodiment, the semiconductor columns have anaverage diameter of at least 0.5 μm or 0.7 μm or 1 μm. Alternatively oradditionally, the average diameter is at most 10 μm or 4 μm or 3 μm.

According to at least one embodiment, a ratio of a mean height and themean diameter of the semiconductor columns is at least 2 or 3 or 5and/or at most 20 or 10 or 7 or 5. By such a ratio of height anddiameter, the semiconductor columns can serve as waveguides for theprimary radiation in the direction parallel to the main emissiondirection.

According to at least one embodiment, the quantum well layers are shapedlike pyramid shells or assembled from a plurality of pyramid shells. Inother words, the quantum well layers can be designed similarly to an eggcarton or napped foam. In this case, the quantum well layers arepreferably shaped like hexagonal pyramids, in particular as viewed as arelief.

According to at least one embodiment, the quantum well layers aresurrounded by further layers of the semiconductor layer sequence on twoopposing main sides. In other words, the quantum well layers can beembedded in the semiconductor layer sequence so that the quantum welllayers do not represent any outer layers of the semiconductor layersequence. The further layers are, for example, cladding layers having arelatively low refractive index to enable a wave guidance of the primaryradiation in the direction perpendicular to the growth direction of thesemiconductor layer sequence.

According to at least one embodiment, the quantum well layers aredesigned to generate different wavelengths of the secondary radiation.In this case, the different wavelengths can be generated in differentregions along the growth direction or in different regions parallel tothe growth direction. For example, quantum well layers are provided forgenerating blue light and/or green light and/or yellow light and/or redlight.

According to at least one embodiment, a spectral half-width of thesecondary radiation, which is generated by the quantum well layers, isat least 40 nm or 60 nm or 80 nm. Thus, the secondary radiation is inparticular mixed-colored light, for example, white light. According toat least one embodiment, the conversion element comprises one or morefurther luminous materials in addition to the quantum well layers,preferably inorganic phosphors. The luminous material specified in thepublication EP 2 549 330 A1 or else quantum dots can be used asphosphors. The at least one luminous material can be one or more of thefollowing substances: Eu²⁺-doped nitrides such as (Ca,Sr)AlSiN₃:Eu²⁺,Sr(Ca,Sr)Si₂Al₂N₆:Eu²⁺, (Sr,Ca)AlSiN₃*Si₂N₂O:Eu²⁺,(Ca,Ba,Sr)₂Si₅N₈:Eu²⁺, (Sr,Ca)[LiAl₃N₄]:Eu²⁺; garnets from the generalsystem (Gd,Lu,Tb,Y)₃(Al,Ga,D)₅(O,X)₁₂:RE where X=halide, N or divalentelement, D=three- or four-valent element and RE=rare earth metals, suchas Lu₃(Al_(1-x)Ga_(x))₅O₁₂:Ce^(3+,) Y₃(Al_(1-x)Ga_(x))₅O₁₂:Ce³⁺;Eu²⁺-doped SiONs such as (Ba,Sr,Ca)Si₂O₂N₂:Eu²⁺; SiAlONs e. g. from thesystem Li_(x)M_(y)Ln_(z)Si_(12-(m+n))Al_((m+n))O_(n)N_(16-n);orthosilicates such as (Ba,Sr,Ca,Mg)₂SiO₄:Eu²⁺.

According to at least one embodiment, an emission surface of thesemiconductor laser for the primary radiation is smaller by at least afactor of 10 or 100 or 1000 than an emission surface of the conversionelement for the secondary radiation and/or the primary radiation. Inother words, an enlargement of an emission surface, relative to theemission surface of the semiconductor laser, takes place in theconversion element.

According to at least one embodiment, the primary radiation does notleave the semiconductor light source during its intended use. In thiscase, the primary radiation is preferably completely or substantiallycompletely converted into the secondary radiation. An additional filterlayer can be located on a light exit side of the conversion element, thefilter layer prevents the primary radiation from leaving thesemiconductor light source.

According to at least one embodiment, the primary radiation is onlypartially converted into the secondary radiation. This means, inparticular, that a mixed radiation is emitted by the semiconductor lightsource, which is composed of the primary radiation and of the secondaryradiation. A power proportion of the primary radiation on the mixedradiation is preferably at least 10% or 15% or 20% and/or at most 50% or40% or 30%.

According to at least one embodiment, the at least one semiconductorlaser and the at least one conversion element are monolithicallyintegrated. This can mean that the semiconductor laser and theconversion element are grown on the same growth substrate and arepreferably still located on the growth substrate. This can likewise meanthat the semiconductor laser and the conversion element are formed froma contiguous semiconductor layer sequence.

BRIEF DESCRIPTION OF THE DRAWINGS

A semiconductor light source described here is explained in more detailbelow with reference to the drawing on the basis of exemplaryembodiments. Identical reference signs indicate the same elements in theindividual figures. In this case, however, no relationships to scale areillustrated; rather, individual elements can be represented with anexaggerated size in order to afford a better understanding.

In the figures:

FIGS. 1 to 18 show schematic sectional representations of exemplaryembodiments of semiconductor light sources;

FIG. 19 shows a schematic perspective illustration of an exemplaryembodiment of a semiconductor light source; and

FIGS. 20A to 20F show schematic sectional representations of tips ofsemiconductor columns for exemplary embodiments of semiconductor lightsources.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

FIG. 1 shows an exemplary embodiment of a semiconductor light source 1.The semiconductor light source 1 comprises a semiconductor laser 2having an active zone 22. The semiconductor laser 2 has a growthdirection H. A primary radiation P exits from the semiconductor laser 2at a light exit region 20 and is emitted towards a conversion element 3.The primary radiation P is generated by means of electroluminescence.

The conversion element 3 of the semiconductor light source 1 contains asemiconductor layer sequence 30 which is optionally located on a growthsubstrate 38. A growth direction G of the semiconductor layer sequence30 can be oriented parallel to the growth direction H of thesemiconductor laser 2.

The semiconductor layer sequence 30 comprises a base region 33 and amultiplicity of semiconductor columns 34 in the base region 33, theprimary radiation P is guided in the direction perpendicular to thegrowth direction G of the semiconductor layer sequence 30. A uniformdistribution of the primary radiation P across the conversion element 3can be achieved by means of the base region 33. The semiconductorcolumns 34 extend from the base region 33. Quantum well layers 31 aregrown on the semiconductor columns 34. The quantum well layers 31represent envelopes to the semiconductor columns 34. Optionally, thequantum wells 31 are covered by a further semiconductor layer 36 or alsoby a protective layer, not shown.

The semiconductor layer sequence is preferably based on a nitridecompound semiconductor material such as Al_(n)In_(1-n-m)Ga_(m)N or on aphosphide compound semiconductor material Al_(n)In_(1-n-m)Ga_(m)P orelse on an arsenide compound semiconductor material such asAl_(n)In_(1--n-m)Ga_(m)As or as Al_(n)Ga_(m)In_(1-n-m)As_(k)P_(1-k),wherein in each case 0≤n≤1, 0≤m≤1 and n+m≤1 and 0≤k<1. Preferably, thefollowing applies to at least one layer or for all layers of thesemiconductor layer sequence 0<n≤0.8, 0.4≤m<1 and n+m≤0.95 and 0<k≤0.5.The semiconductor layer sequence can have dopants and additionalcomponents. For the sake of simplicity, however, only the essentialcomponents of the crystal lattice of the semiconductor layer sequenceare mentioned, that is, Ga, In, N or P, even if these can be partiallyreplaced and/or supplemented by small quantities of further substances.The semiconductor layer sequence is preferably based onAl_(n)In_(1-n-m)Ga_(m)N, as in all other exemplary embodiments.

The semiconductor columns 34 form a waveguide for the primary radiationP in the direction parallel to the growth direction G. The primaryradiation P exits the semiconductor columns 34 at tips 35 of thesemiconductor columns 34, passes through the quantum well layers 31 andis converted into a secondary radiation S. A mixture of the secondaryradiation S and the primary radiation P is thus emitted at the tips 35.Alternatively, it is possible for only the secondary radiation S toemerge from the conversion element 3.

Both the semiconductor laser 2 and the conversion element 3 are locatedon a common carrier 4, which can also contain further electroniccomponents (not shown), for example, for controlling the semiconductorlaser 2.

According to FIG. 1, the tips 35 of the semiconductor columns 34 are ofpyramid-shaped design, for example, as hexagonal pyramids. Seen in crosssection, the quantum well layers 31 therefore have kinks. Unlike in FIG.1, it is also possible for the quantum well layers 31 to be restrictedonly to the tips 35 so that a region between the semiconductor columns34 and/or side surfaces of the semiconductor columns 34 is then free ofthe quantum well layers 31.

The conversion element 3 is a structure similar to an LED, whereinelectrical contact layers and current spreading layers can be dispensedwith, since the secondary radiation S is generated by photoluminescence.Through the quantum well layers, for example, by the thickness and/ormaterial composition thereof, a wavelength of the secondary radiation Scan be set in a targeted manner over a wide range. Since no electricalcontact layers or current spreading layers need to be present, anefficiency of the photoluminescence can be increased compared toelectroluminescence in a conventional light-emitting diode. Furthermore,a base area of the conversion element is substantially freely scalable.In addition, a light intensity of the semiconductor light source 1 canbe set by using different and/or a plurality of semiconductor lasers 2.

In other words, the primary radiation P, which is laser radiation, iscoupled into the conversion element 3 as a beam-shaping element, forinstance into a lateral chip flank of an LED chip on the basis of thematerial system InGaN with a sapphire growth substrate 38. Theconversion element 3 contains a waveguide with an optically activecoupling-out structure, formed by the semiconductor columns 34. Theprimary radiation P couples into the base region 33 and is coupled outvia the semiconductor columns 34. The optically active layer in the formof the quantum well layers is located on a surface of the semiconductorcolumns 34 serving as the coupling-out structure, which is pumped by thelaser light of the primary radiation P. Thus, an efficient, scalablelight source having an adjustable color can be produced without havingto use expensive optics.

For example, the semiconductor laser 2 is a laser having a main emissionwavelength at approximately 405 nm, as used for blu-rays. In this case,the primary radiation P is preferably completely converted into thesecondary radiation S.

Because of the wave guidance of the primary radiation P in thesemiconductor columns 34 and because of the design of the tips 35 it isachieved that the secondary radiation and/or the primary radiation Pis/are predominantly emitted in the direction parallel or approximatelyparallel to the growth direction G so that a dedicated main emissiondirection M results. Radiation through the conversion element 3 is thusspatially narrower than in the case of a Lambertian emitter.

A further exemplary embodiment is illustrated in FIG. 2. In contrast toFIG. 1, the semiconductor columns 34 are rectangular in cross section sothat the tips 35 are oriented perpendicular to the growth direction G.Furthermore, a mirror 5 is provided which extends between the optionalgrowth substrate 38, which is in particular made of sapphire, and thecarrier 4. Such a mirror 5 can also be present in all other exemplaryembodiments and is, for example, a metallic mirror or a dielectricmultilayer or single-layer mirror or a combination of at least onedielectric layer and at least one metal layer or semiconductor layer.

Furthermore, a luminous material 37 is additionally present in theconversion element 3. An additional secondary radiation S2 can begenerated via the luminous material 37, in particular in a differentcolor than the secondary radiation S directly from the quantum welllayers 31.

The luminous material 37 is formed, for example, by inorganic phosphorparticles which are embedded in a uniformly distributed manner in amatrix material, for example, a silicone or an epoxide. The secondaryradiation S2 is preferably generated essentially in regions above thetips 35 of the semiconductor columns 34.

In the exemplary embodiment of FIG. 3, the quantum well layers 31 areattached to the semiconductor columns 34, which are shaped as atrapezoid in each case when viewed in cross section, wherein thesemiconductor columns 34 taper in the direction away from the baseregion 33.

As also possible in all other exemplary embodiments, the luminousmaterial 37 can imitate a shape of the semiconductor columns 34 so thata height of the luminous material 37, relative to the base region 33,directly above the semiconductor columns 34 can be larger than inregions between the semiconductor columns 34. In this case, a side ofthe luminous material 37 facing away from the base region 33 can imitatethe semiconductor columns 34 not only exactly but also in approximationor in a smoothed manner.

Optionally, it is also possible for phosphor particles to be present inregions between the semiconductor columns 34 in a reduced concentrationor that the phosphor particles are restricted to a region above the tips35.

Optionally, as in all other exemplary embodiments, a further mirror 5 bis present, in addition to the mirror 5 a between the carrier 4 and thesemiconductor layer sequence 30. The mirror 5 b is orientedperpendicular to a beam direction of the primary radiation P. Theprimary radiation P can be distributed more uniformly in the base region33 by means of the mirror 5 b.

A further exemplary embodiment is illustrated in FIG. 4. As in all otherexemplary embodiments, it is possible that more than one semiconductorlaser 2 is used; according to FIG. 4, two of the semiconductor lasers 2are present.

The luminous material 37 is designed as a plate or platelet havingapproximately plane-parallel main sides. Thus, an intermediate spacebetween adjacent semiconductor columns 34 is free of the luminousmaterial 37.

The quantum well layers 31 are located on tips of the semiconductorcolumns 34 which originate from the base region 33. Optionally, afurther semiconductor material 36 is located above the quantum welllayers 31, in the direction away from the base region 33, for example,to protect the quantum well layers 31. The platelet with the luminousmaterial 37 is thus either applied to the further semiconductor material36 or, in contrast to the illustration in FIG. 4, is applied directly tothe quantum well layers 31. In this case, the luminous material 37 canbe adhesively bonded, for example, via a transparent, for instancesilicone-containing adhesive. Unlike in FIG. 4, a transparent, opticallynon-active adhesive or residues thereof can extend into a region betweenthe semiconductor columns 34.

In FIGS. 1 to 4, different embodiments of the semiconductor columns 34,of the luminous material 37 and of the mirrors 5 are drawn. Thesedifferent configurations of the individual components can in each casebe transferred to the other exemplary embodiments. For example, themirrors 5 a, 5 b from FIG. 3 can also be used in the exemplaryembodiments of FIGS. 1, 2 and 4, or the semiconductor columns 34 fromFIG. 1 can be present in FIGS. 2, 3 and 4.

In the exemplary embodiment of FIG. 5, the quantum well layers 31 arecomposed of pyramid-shaped parts, similarly to napped foam. This isachieved, for example, in that on a growth layer 32, which is based, forexample, on GaN, a mask layer 6, for instance made of silicon dioxide,is applied. Proceeding from openings in the mask layer 6, pyramid-shapedbase regions 33 are grown, on which the quantum well layers 31 areformed. Optionally, the further semiconductor layer 36, for instancemade of GaN, is present, which can lead to a planarization. In otherwords, the base regions are three-dimensionally grown, the quantum welllayers 31 are applied to the base regions 33 true to shape, and thefurther semiconductor layer 36 is a two-dimensionally grown layer.

As in all other exemplary embodiments, it is also possible for claddinglayers 39 having a lower refractive index to be present, in order toensure guidance of the primary radiation P in the directionperpendicular to the growth direction G. Optionally present mirrors arenot shown in FIG. 5. Such a mirror is represented schematically in FIG.6, for example.

In the exemplary embodiment of FIG. 7, deviating from FIG. 5, aroughening 7 is present on a side of the semiconductor layer sequence 30facing away from the growth layer 32. By means of such a roughening 7,an emission characteristic can be influenced and a more efficient lightoutput can also be achieved.

In the exemplary embodiment of FIG. 8, the luminous material 37 isadditionally present as a layer on the semiconductor layer sequence 30.

FIG. 9 schematically illustrates that the conversion element 3 comprisesdifferent semiconductor columns 34 with differently designed quantumwells. As a result, in different regions of the conversion element 3,viewed in a plan view, secondary radiation S1, S2, S3 having differentwavelengths is emitted. It is thus possible for mixed-colored whitelight to be generated by the semiconductor light source 1, in particularcomposed only from the secondary radiations S1, S2, S3.

According to FIG. 10, a mirror 5 is additionally present, which can bedesigned as a Bragg mirror with a plurality of layers with alternatelyhigh and low refractive indices. Such a mirror is composed, inparticular, of dielectric layers, and can have a profile with regard toa reflection wavelength and can thus be designed as a so-called chirpedmirror. According to FIG. 10, the mirror 5 covers an underside of thebase region 33 facing away from the semiconductor columns 34 and an endface of the base region 33 opposite the semiconductor laser 2.

A mirror 5 is also present in FIG. 11. The mirror 5 can be, as in allother exemplary embodiments, a metallic reflector, for example, withsilver and/or aluminum. Possible protective layers for the mirror 5 arenot shown in FIG. 11. The mirror 5 completely covers a bottom surfaceand side surfaces of the conversion element 3, with the exception of alight entrance opening for the primary radiation P. It is optionallypossible that a side of the semiconductor columns 34 which faces awayfrom the base region 33 is covered by the mirror 5 in a small part allaround an edge.

A further exemplary embodiment is illustrated in FIG. 12. In this case,the semiconductor laser 2 is mounted on a heat sink 81 and is contactedvia electrical connections 83 out of a housing body 82. Thesemiconductor light source 1 can be configured as a so-called TO design.

The semiconductor layer sequence 30 with the semiconductor columns 34 isarranged on a carrier 38, in particular a growth substrate for thesemiconductor layer sequence 30. The primary radiation P is irradiatedinto the semiconductor layer sequence 30 in the direction parallel tothe growth direction G and is partially converted into the secondaryradiation S. Thus, a mixture of the secondary radiation S and theprimary radiation P is emitted through a light exit window 84. Incontrast to the illustration, the light exit window 894, as in all otherexemplary embodiments, can be designed as an optical element such as alens.

According to FIG. 13, a plurality of semiconductor layers 30 havingdifferent quantum well layers 31 a, 31 b are present. Each of thequantum well layers 31 a, 31 b generates a secondary radiation S1, S2 ofa particular color. Thus, mixed-colored light, which can be free of theprimary radiation P, is generated by the quantum well layers 31 a, 31 b.

According to FIG. 14, an optical system 9 is located between thesemiconductor laser 2 and the conversion element 3, the optical system 9is preferably also present in all other exemplary embodiments of FIGS.12 and 13. A uniform or substantially uniform illumination of thequantum well layers 31 with the primary radiation P is achieved via theoptical system 9. For example, the optical system 9 is a cylindricallens.

In the exemplary embodiment of FIG. 15, the quantum well layers 31 arelocated in the base region 33 and are oriented perpendicular to thegrowth direction G. In contrast to FIG. 15, according to FIG. 16 thequantum well layers 31 are located in the semiconductor columns 34. Inthis case, in particular the planar quantum well layers 31 and a regionfor the subsequent semiconductor columns 34 are first grown, only thenare the semiconductor columns 34 prepared for instance by etching. Thequantum well layers 31 can thus lie in the interior of the semiconductorcolumns 34 or also below the base region 33 as a flat quantum film.

Further, these statements with regard to the semiconductor laser 2, thecladding layer 39, the growth substrate 38 and the luminous material 37to FIGS. 1 to 4 apply correspondingly to FIGS. 15 and 16.

In the semiconductor light source 1 of FIGS. 17 and 18, thesemiconductor laser 2 and the conversion element 3 are monolithicallyintegrated on a common growth substrate 38. In this case, the quantumwell layers 31 are located in or near a waveguide of the semiconductorlaser 2 for the primary radiation P so that as much primary radiation Pas possible can be scattered out of the waveguide and an efficientcoupling to the quantum well layers 31 takes place. The active zone 22of the semiconductor laser 2 and the quantum well layers 31 arepreferably spatially separated from one another in this case.

In this case, the active zone 22 of the semiconductor laser 2 in FIG. 17is applied to a region next to the semiconductor columns 34, viewed in aplan view. Thus, for example, the semiconductor columns 34 arrangedabove the semiconductor laser 2, along the growth direction G, areremoved, but preferably not the base region 33. In contrast to theillustration, a gap can be located between the semiconductor laser 2 andthe conversion element 3, in order to optimize resonator mirrors of thesemiconductor laser 2, for example.

FIG. 18 shows that the active zone 22 of the semiconductor laser 2 alsoextends continuously over the conversion element 3 so that the quantumwell layers 31 and the active zone 22 are stacked one on top of theother. For better electrical contacting, the base region 33 can beremoved in the area next to the semiconductor columns 34, in contrast toFIG. 17. It is possible that a generation of the primary radiation P isalso restricted to the area next to the semiconductor columns 34, viewedin a plan view, analogously to FIG. 17.

FIG. 19 shows that the semiconductor laser 2 is a so-called stripelaser, also referred to as a ridge laser. The primary radiation P isemitted linearly. In this case, the line on the conversion element 3runs perpendicular to the growth direction G of the semiconductor layersequence 30. A corresponding arrangement is preferably also selected inconjunction with the exemplary embodiments of FIG. 1 to 11, 15 or 16.

FIG. 20 shows further shapes of the tips 35. Such tips 35 can also beused in all other exemplary embodiments, wherein a plurality ofdifferent tip types can be combined with one another within a singleconversion element 3.

According to FIG. 20A, the tip 35 is of rectangular design, seen incross section. The tip 35 has a smaller width than the remaining part ofthe semiconductor column 34.

Deviating from the representations in FIG. 20, the semiconductor columns34 can also each have no special tips and appear rectangular when viewedin cross section, as is illustrated, for example, in FIG. 2, and as isalso possible in all other exemplary embodiments. The semiconductorcolumns 34 can thus be formed cylindrically without a pointed structure.

In FIG. 20B it is shown that the tip 35 is triangular when viewed incross section, wherein a flank angle, in comparison with FIG. 1, isrelatively large so that an opening angle of the triangle, furthest awayfrom the base region 33, is, for example, at most 60° or 45° or 30°.According to FIG. 20C, a semicircular shape is present and, according toFIG. 20D, a trapezoidal shape of the tip 35 is present.

According to FIG. 20E, the tip 35 is parabolic and has a smallerdiameter than remaining regions of the semiconductor column 34, as canalso apply correspondingly in FIG. 20B, 20C or 20D. Finally, see FIG.20F, the tip 35 is designed as a stepped pyramid.

An average diameter of the semiconductor columns is preferably at leastλ/4n, wherein λ is the wavelength of maximum intensity of the primaryradiation P and n is the refractive index of the semiconductor columns34. The diameter is preferably between 5λ/n and 10λ/n. A typicaldiameter can also lie at approximately 2λ/n. An aspect ratio of adiameter and a height of the semiconductor columns is preferably at most1 or 0.5 or 0.2.

The invention described here is not restricted by the description on thebasis of the exemplary embodiments. Rather, the invention encompassesany new feature and also any combination of features, which includes inparticular any combination of features in the patent claims, even ifthis feature or this combination itself is not explicitly specified inthe patent claims or exemplary embodiments.

What is claimed is:
 1. A semiconductor light source comprising: at leastone semiconductor laser configured to generate a primary radiation; andat least one conversion element configured to generate a longer-wavevisible secondary radiation from the primary radiation, wherein theconversion element comprises a semiconductor layer sequence having oneor more quantum well layers, wherein, in operation, the primaryradiation is irradiated into the semiconductor layer sequence parallelto a growth direction thereof, with a tolerance of at most 15°, wherein,in operation, the semiconductor layer sequence is homogeneouslyilluminated with the primary radiation, and wherein a growth substrateof the semiconductor layer sequence is located between the semiconductorlayer sequence and the semiconductor laser, the growth substrate beingoriented perpendicular to the growth direction.
 2. The semiconductorlight source according to claim 1, wherein the one or more quantum welllayers are three-dimensionally shaped so that the one or more quantumwell layers have kinks when viewed in cross section and are oriented atleast in places obliquely to the growth direction of the semiconductorlayer sequence.
 3. The semiconductor light source according to claim 1,wherein the conversion element has a continuous base region andsemiconductor columns extending away from the base region.
 4. Thesemiconductor light source according to claim 3, wherein the one or morequantum well layers are arranged on the semiconductor columns, wherein,in operation, an emission of at least one of the secondary radiation andof the primary radiation from the semiconductor columns occurs to atleast 50 percent on tips of the semiconductor columns.
 5. Thesemiconductor light source according to claim 3, wherein thesemiconductor columns have an average diameter of between 0.5 μm and 20μm inclusive, and a ratio of a mean height of the semiconductor columnsand the average diameter is between 3 and 26 inclusive.
 6. Thesemiconductor light source according to claim 3, wherein the one or morequantum well layers are located in the base region and are orientedperpendicular to the growth direction, and wherein the one or morequantum well layers lie in an interior of the semiconductor columns. 7.The semiconductor light source according to claim 1, wherein the one ormore quantum well layers are pyramid shaped or are composed of pyramidshapes, and wherein the one or more quantum well layers are surroundedby further layers of the semiconductor layer sequence on two main sideslying opposite one another.
 8. The semiconductor light source accordingto claim 1, wherein the one or more quantum well layers are configuredto generate different wavelengths of the secondary radiation, andwherein a spectral half-width of the secondary radiation, which isgenerated by the quantum well layers, is at least 60 nm.
 9. Thesemiconductor light source according to claim 1, wherein the conversionelement additionally comprises at least one luminous material.
 10. Thesemiconductor light source according to claim 9, wherein the luminousmaterial is doped with at least one rare earth.
 11. The semiconductorlight source according to claim 9, wherein the luminous material isselected from the group consisting of oxide, nitride, oxynitride,garnet, sulfide, silicate, phosphate and halide.
 12. The semiconductorlight source according to claim 1, wherein an emission surface of thesemiconductor laser for the primary radiation is smaller by at least afactor of 100 than an emission surface of the conversion element for thesecondary radiation.
 13. The semiconductor light source according toclaim 1, wherein the primary radiation does not leave the semiconductorlight source during operation, and wherein a wavelength of maximumintensity of the primary radiation is between 360 nm and 490 nminclusive.
 14. The semiconductor light source according to claim 1,wherein, in operation, the primary radiation is only partially convertedinto the secondary radiation so that a mixed radiation is emitted by thesemiconductor light source, which is composed of the primary radiationand of the secondary radiation, a power proportion of the primaryradiation on the mixed radiation is at least 20 percent and at most 50percent.
 15. The semiconductor light source according to claim 1,wherein an optical system is located between the semiconductor laser andthe conversion element.
 16. The semiconductor light source according toclaim 15, wherein the optical system is a cylindrical lens.
 17. Thesemiconductor light source according to claim 1, wherein thesemiconductor laser is mounted distant from the growth substrate on aheat sink at a bottom of a cavity in a TO housing body and configured tobe contacted via electrical connections out of the TO housing body,wherein the growth substrate with the semiconductor layer sequence isfixed to side walls of the TO housing body and is followed by a lightexit window which is an optical element.